Accommodation cassette

ABSTRACT

An accommodation cassette including: a plurality of rear accommodating grooves that are formed at least in the laterally central area of the inner surface of a rear wall connecting the rear edges of right and left side walls and extend laterally and parallel to each other at vertical spacings in such a manner as to be associated with right and left accommodating grooves.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an accommodation cassette foraccommodating a frame unit having a wafer attached thereto via anattachment tape in an opening formed at the central portion of the frameunit or directly accommodating a wafer without a frame unit.

2. Description of the Related Art

As is known to those skilled in the art, an accommodation cassette iswidely used to accommodate frame units each having a wafer attachedthereto via an attachment tape in an opening formed at the centralportion of the frame unit or directly accommodate wafers each without aframe unit. The cassette has two side walls, i.e., right and left sidewalls, provided parallel to each other with a given spacingtherebetween. A plurality of right accommodating grooves are formed onthe inner surface of the right side wall. The right accommodatinggrooves are formed at vertical spacings and extend longitudinally andparallel to each other. A plurality of left accommodating grooves areformed on the inner surface of the left side wall in such a manner as tobe associated with the right accommodating grooves. The leftaccommodating grooves are formed at vertical spacings and extendlongitudinally and parallel to each other.

According to the experience of the present inventor, however, it hasbeen found that there is a tendency that, during manual placement of aframe unit or wafer into the above conventional accommodation cassette,a specific right accommodating groove and a left accommodating grooveone above or below the groove associated with the specific rightaccommodating groove are erroneously selected. Placing a frame unit orwafer into the cassette with a wrong pair of right and leftaccommodating grooves may damage the wafer during placement of the frameunit or wafer or result in failure to extract the frame unit or wafer ordamage the wafer during automatic extraction of the frame unit or waferfrom the accommodation cassette by means of a wafer handling mechanism.

In order to solve the above problem with the conventional accommodationcassette, Japanese Patent Laid-Open No. Hei 7-117810 discloses easyidentification of adjacent grooves of each of the right and leftaccommodating grooves by alternately changing the protrusion lengths orcolors of the protruding pieces that define the right and leftaccommodating grooves on the inner surfaces of the right and left sidewalls of the accommodation cassette. Further, Japanese Patent Laid-OpenNo. Hei 9-27543 discloses easy identification of adjacent grooves ofeach of the right and left accommodating grooves by forming a notch atthe front edge portion of every other protruding piece that defines eachof the right and left accommodating grooves on the inner surfaces of theright and left side walls of the accommodation cassette.

SUMMARY OF THE INVENTION

Then, the accommodation cassettes disclosed in Japanese Patent Laid-OpenNos. Hei 7-117810 and Hei 9-27543 can comparatively easily identifyadjacent grooves of each of the right and left accommodating groovesbased on the protrusion length, color or presence or absence of a notch.According to the experience of the present inventor, however, thesecassettes are yet to be fully satisfactory. Instead, it has been foundthat there is still a likelihood that a specific right accommodatinggroove and a left accommodating groove not associated therewith may beerroneously selected during placement of a frame unit or wafer.

Therefore, it is an object of the present invention to provide a new andimproved accommodation cassette for positively preventing the selectionof a wrong pair of right and left accommodating grooves during placementof a frame unit or wafer into the cassette.

In accordance with an aspect of the present invention, there is providedan accommodation cassette that includes right and left side walls, arear wall, a plurality of right accommodating grooves, a plurality ofleft accommodating grooves and a plurality of rear accommodatinggrooves. The left side wall is provided parallel to the right side wall.The rear wall connects the rear edges of the right and left side walls.The right accommodating grooves are formed on the inner surface of theright side wall and extend longitudinally and parallel to each other atgiven vertical spacings. The left accommodating grooves are formed onthe inner surface of the left side wall and extend longitudinally andparallel to each other at the given vertical spacings in such a manneras to be associated with the right accommodating grooves. The rearaccommodating grooves are formed at least in the laterally central areaof the inner surface of the rear wall and extend laterally and parallelto each other at the vertical spacings in such a manner as to beassociated with the right and left accommodating grooves.

A plurality of protruding pieces should preferably be formed in thelaterally central area of the inner surface of the rear wall and extendlaterally and parallel to each other at vertical spacings, and the rearaccommodating grooves should preferably be defined by the protrudingpieces.

In the case of the accommodation cassette according to the presentinvention, when a specific right accommodating groove and a leftaccommodating groove associated therewith are correctly selected, theright and left side portions of the frame unit or wafer are insertedrespectively into the right and left accommodating grooves. At the sametime, the rear edge portion of the frame unit or wafer is inserted intothe rear accommodating groove, thus allowing the frame unit or wafer tobe placed into the accommodation cassette as required. On the otherhand, if a specific right accommodating groove and a left accommodatinggroove one above or below the groove associated with the specific rightaccommodating groove are erroneously selected during placement of aframe unit or wafer, the rear edge portion of the frame unit or waferbecomes tilted relative to the rear accommodating groove, thus making itimpossible to insert the rear edge portion of the frame unit or waferinto the rear accommodating groove. This leads to failure of the frameunit or wafer to be inserted rearward to the required position in theaccommodation cassette, thus resulting, for example, in the front edgeportion of the frame unit or wafer protruding from the front surface ofthe accommodation cassette. This allows the operator to recognize thefact that the right and left accommodating grooves have been erroneouslyselected so as to correct the selection thereof. As a result, it ispossible to positively prevent the selection of a wrong pair of rightand left accommodating grooves during placement of a frame unit or waferinto the cassette.

The above and other objects, features and advantages of the presentinvention and the manner of realizing them will become more apparent,and the invention itself will best be understood from a study of thefollowing description and appended claims with reference to the attacheddrawings showing a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating, in a partially cut-outmanner, a preferred embodiment of an accommodation cassette configuredaccording to the present invention;

FIG. 2 is a front view of the accommodation cassette shown in FIG. 1;and

FIG. 3 is a perspective view of a typical example of a frame to which awafer is attached.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A detailed description will be given below of a preferred embodiment ofan accommodation cassette 1 configured according to the presentinvention with reference to the accompanying drawings. Referring toFIGS. 1 and 2, the accommodation cassette 1 illustrated in these figuresis in the shape of a rectangular parallelepiped as a whole and has apair of side walls, i.e., right and left side walls 2 and 4, a rear wall6, an upper wall 8 and a lower wall 10. The right and left side walls 2and 4 are rectangular in shape, provided at given lateral spacings andextend substantially orthogonally. The rear wall 6 connects the rearedges of the right and left side walls 2 and 4, is rectangular in shapeand extends substantially orthogonally. The upper wall 8 is rectangularin shape and extends substantially horizontally. The lower wall 10extends between the lower edges of the right and left side walls 2 and4. In the present embodiment, the right and left side walls 2 and 4 andthe rear wall 6 are rectangular in shape, with the right and left sidesurfaces and rear surface of the accommodation cassette 1 beingcompletely closed. On the other hand, the upper wall 8 has a trapezoidalnotch 9 formed in its front edge portion, with the upper surface of theaccommodation cassette 1 being open. Further, the lower wall 10 is inthe form of a belt extending substantially horizontally between thelongitudinally intermediate areas of the right and left side walls 2 and4, with the front and rear edge portions of the lower surface of theaccommodation cassette 1 being open. A gate-shaped grip piece 12 isattached on the upper surface of the upper wall 8. The same piece 12 cangrip the accommodation cassette 1 during transportation thereof. Theentire front surface of the accommodation cassette 1 is open. Theaccommodation cassette 1 configured as described above can beconveniently formed by molding, in one piece, whole of the same cassette1 with an appropriate synthetic resin or properly joining a plurality ofcomponents, each molded from an appropriate synthetic resin, together.

A plurality of parallel right accommodating grooves 14 are formed on theinner surface of the right side wall 2. The parallel right accommodatinggrooves 14 are formed at equal vertical spacings and extendsubstantially horizontally in the longitudinal direction. Similarly, aplurality of parallel left accommodating grooves 16 are formed on theinner surface of the left side wall 4 in such a manner as to beassociated with the parallel right accommodating grooves 14. Theparallel left accommodating grooves 16 extend substantially horizontallyin the longitudinal direction. The right and left accommodating grooves14 and 16 are provided in such a manner as to be associated with eachother. The same grooves 14 and 16 are plane-symmetrical with respect toan intermediate plane extending parallel to and midway between the rightand left side walls 2 and 4.

In the accommodation cassette 1 configured according to the presentinvention, it is important that a plurality of rear accommodatinggrooves 18 should be formed at least in the laterally central area ofthe inner surface of the rear wall 6 and extend substantiallyhorizontally in the lateral direction at vertical spacings in such amanner as to be associated with the right and left accommodating grooves14 and 16. In the present embodiment, a plurality of parallel protrudingpieces 20 are formed in the laterally intermediate area of the rear wall6. The same protruding pieces 20 are formed on the inner surface of therear wall 6 and extend substantially horizontally at equal verticalspacings. Each of the rear accommodating grooves 18 is defined betweenthe two protruding pieces 20. The vertical position and width of each ofthe rear accommodating grooves 18 matches those of each of the right andleft accommodating grooves 14 and 16. If desired, it is possible to formthe rear accommodating grooves 18 that extend laterally across the rearwall 6 rather than in the laterally central area of the rear wall 6.

FIG. 3 illustrates a frame 22 which is in itself a known form. The frame22 is placed into the accommodation cassette 1 shown in FIGS. 1 and 2. Acircular opening 24 is formed at the center of the frame 22 that can beformed from an appropriate synthetic resin or thin metal plate, with anapproximately circular wafer 26 attached in the opening 24. Describingfurther in detail, a continuously extending attachment tape 28 isaffixed to the rear surfaces of the frame 22 and wafer 26. The wafer 26is attached to the frame 22 via the attachment tape 28, thus forming aframe unit 25.

As illustrated by a two-dotted line 22A in FIGS. 1 and 2, the frame unit25 is inserted into the accommodation cassette 1 from the front surfacethereof which is left open. The right side portion of the same unit 25is placed into the specific right accommodating groove 14, the left sideportion of the same unit 25 is placed into the specific leftaccommodating groove 16 associated with the specific right accommodatinggroove 14, and further, the rear edge portion of the same unit 25 isplaced into the specific rear accommodating groove 18 associated withthe specific right and left accommodating grooves 14 and 16, thusallowing the frame unit 25 to be placed into the accommodation cassette1. As illustrated by a two-dotted line 22B in FIGS. 1 and 2, on theother hand, if, for example, the specific right accommodating groove 14and the left accommodating groove 16 one below the groove associatedwith the specific right accommodating groove 14 are erroneouslyselected, the frame unit 25 is inserted into the accommodation cassette1 with its left side tilted down. In this case, because of the insertionof the frame unit 25 into the accommodation cassette 1 in a tiltedmanner, it is impossible to place the rear edge portion of the frameunit 25 into the rear accommodating groove 18 formed on the rear wall 6.As a result, the front edge of the frame unit 25 is located more forwardthan normal as illustrated by the two-dotted line 22B in FIG. 1, thusresulting, for example, in the front edge portion of the same unit 25protruding from the front surface of the accommodation cassette 1.Therefore, it is possible for the operator to clearly recognize the factthat the left accommodating groove 16 (or right accommodating groove 14)has been erroneously selected, thus allowing the operator to correct theselection of the left accommodating groove 16 (or right accommodatinggroove 14), select the appropriate left accommodating groove 16 (orright accommodating groove 14), and place the frame unit 25 into theaccommodation cassette 1 as required. This positively prevents theinsertion of the frame unit 25 into the accommodation cassette 1 in aninappropriate condition as a result of erroneous selection of the leftaccommodating groove 16 (or right accommodating groove 14), i.e., insuch a manner that the frame unit 25 is laterally tilted.

A detailed description has been given above of a preferred embodiment ofthe accommodation cassette 1 configured according to the presentinvention with reference to the accompanying drawings. However, thepresent invention is not limited to the embodiment. Instead, there is noneed to dwell on the fact that the present invention can be modified oraltered in various ways without departing from the scope of the presentinvention. For example, while the accommodation cassette 1 foraccommodating the frame unit 25 to which a wafer is attached has beendescribed, the present invention is applicable to the accommodationcassette 1 for directly accommodating wafers each without the frame unit25.

The present invention is not limited to the details of the abovedescribed preferred embodiment. The scope of the invention is defined bythe appended claims and all changes and modifications as fall within theequivalence of the scope of the claims are therefore to be embraced bythe invention.

What is claimed is:
 1. An accommodation cassette comprising: a rightside wall; a left side wall provided parallel to the right side wall; arear wall adapted to connect the rear edges of the right and left sidewalls; a plurality of right accommodating grooves that are formed on theinner surface of the right side wall and extend longitudinally andparallel to each other at vertical spacings; a plurality of leftaccommodating grooves that are formed on the inner surface of the leftside wall and extend longitudinally and parallel to each other at thevertical spacings in such a manner as to be associated with the rightaccommodating grooves; and a plurality of rear accommodating groovesthat are formed at least in the laterally central area of the innersurface of the rear wall and extend laterally and parallel to each otherat the vertical spacings in such a manner as to be associated with theright and left accommodating grooves.
 2. The accommodation cassette ofclaim 1, wherein a plurality of protruding pieces are formed in thelaterally central area of the inner surface of the rear wall and extendlaterally and parallel to each other at vertical spacings, and whereinthe rear accommodating grooves are defined by the protruding pieces.